Abstract：
Biofilm detachment contributes to water quality deterioration. However, the contributions of biofilm detachment from different pipes have not been quantified or compared. Following the introduction of partial reverse osmosis (RO) in drinking water production, this study analyzed particles at customers\' ends and tracked their origins to water distribution mains and service lines. For doing so, filter bags were installed in front of water meters to capture upstream detached particles, while biofilm from water main and service line were sampled by cutting pipe specimens. The results showed that elemental concentrations of the biofilm in mains were higher than those of service lines (54.3-268.5 vs. 27.1-44.4 μg/cm2), both dominated by Ca. Differently, filter bags were dominated by Fe/Mn (77.5-98.1%). After introducing RO, Ca significantly decreased in biofilms of mains but not service lines, but the released Fe/Mn rather than Ca arrived at customers\' ends. The ATP concentrations of service lines were higher than mains, which decreased on mains but increased in service lines after introducing RO. For the core ASVs, 13/24 were shared by service lines (17), mains (21), and filter bags (17), which were assigned mainly to Nitrospira spp., Methylomagnum spp., Methylocytis spp., and IheB2-23 spp. According to source tracking results, service lines contributed more than mains to the particulate material collected by filter bags (57.6 ± 13.2% vs. 13.0 ± 11.6%). To the best of our knowledge, the present study provides the first evidence of service lines\' direct and quantitative contributions to potential water quality deterioration at customers\' ends. This highlights the need for the appropriate management of long-neglected service line pipes, e.g., regarding material selection, length optimization, and proper regulation.
摘要：
生物膜脱离导致水质恶化。然而,生物膜从不同管道分离的贡献尚未量化或比较。在饮用水生产中引入部分反渗透（RO）之后，这项研究分析了客户端的颗粒，并跟踪了它们的来源到水分配干线和服务线。为了这样做，滤袋安装在水表前，以捕获上游分离的颗粒，同时通过切割管道标本对来自水主管和服务线的生物膜进行采样。结果表明，干线中生物膜的元素浓度高于服务线（54.3-268.5vs.27.1-44.4μg/cm2)，两者都由Ca主导。不同的是,滤袋以Fe/Mn（77.5-98.1％）为主。在介绍RO之后,Ca在干线生物膜中显著下降，但在服务线路中却没有，但释放的铁/锰而不是钙到达客户端。服务线路的ATP浓度高于干线，引入RO后，干线减少，但服务线路增加。对于核心ASV，13/24由服务项目共享(17)，电源(21),和过滤袋(17)，主要分配给硝基螺旋体。,甲藻属。,甲基囊炎。,和IheB2-23spp。根据来源追踪结果，服务线对过滤袋收集的颗粒材料的贡献超过干线(57.6±13.2%与13.0±11.6%）。据我们所知,本研究提供了服务线对客户潜在水质恶化的直接和定量贡献的第一个证据。这凸显了对长期被忽视的服务管线管道进行适当管理的必要性,例如，关于材料选择，长度优化，和适当的监管。
